Palladium asymmetric reduction of β-carboline imines mediated by chiral auxiliaries assisted by microwave irradiation

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• 作者：Marlene Espinoza-Moraga ; Ana Gloria Caceres ; Leonardo Silva Santos
• 关键词：Palladium asymmetric reduction ; Tetrahydro-β ; -carboline ; Enantioselective synthesis ; Chiral auxiliaries
• 刊名：Tetrahedron Letters
• 出版年：2009
• 出版时间：16 December 2009
• 年：2009
• 卷：50
• 期：50
• 页码：7059-7061
• 全文大小：291 K

文摘

An alternative synthetic approach for the introduction of chirality in β-carboline moiety through in situ reduction of N-acyliminium ion intermediates generated from imine 2 and chloroformate of 8-phenylmenthyl as chiral auxiliary was achieved. The method applied microwave-assisted irradiation and used PdCl₂/Et₃SiH protocol as a mild reducing agent, which decreased reaction times to minutes when compared to the conventional thermal reactions. The diastereoselectivity (4–12:1) of the reduction produced R-amines, which were assigned after chiral auxiliary removal and spectroscopic data compared to products obtained from Noyori asymmetric hydrogenation catalyst.